Rotational rate sensors based on the Coriolis effect have been commercially produced in the form of a micro-miniature double-ended quartz tuning forks. Such vibrating quartz tuning forks are generally composed of a single wafer of monocrystalline piezoelectric quartz. One use of such a rate sensor is as a yaw sensor in a motor vehicle. Because of the above use in automotive applications it is desired to have a device which is the most economical, miniaturized, and which is compatible with other semiconductive components of the automobile.
Silicon devices have been proposed but as yet have not become commercially available because of processing difficulties compared to the commercial quartz-based device. For example, one type of silicon device is constructed of polycrystalline silicon whose limited thickness is detrimental to sensitivity.